| Message ID | 20210309000247.2989531-2-danielwa@cisco.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v2,1/7] CMDLINE: add generic builtin command line | expand |
Le 09/03/2021 à 01:02, Daniel Walker a écrit : > This code allows architectures to use a generic builtin command line. > The state of the builtin command line options across architecture is > diverse. On x86 and mips they have pretty much the same code and the > code prepends the builtin command line onto the boot loader provided > one. On powerpc there is only a builtin override and nothing else. Same comment as in v1: The above is not correct for powerpc. > > The code in this commit unifies the code into a generic > header file under the CONFIG_GENERIC_CMDLINE option. When this > option is enabled the architecture can call the cmdline_add_builtin() > to add the builtin command line. > > Cc: xe-linux-external@cisco.com > Signed-off-by: Ruslan Bilovol <rbilovol@cisco.com> > Signed-off-by: Daniel Walker <danielwa@cisco.com> > --- > include/linux/cmdline.h | 89 +++++++++++++++++++++++++++++++++++++++++ > init/Kconfig | 68 +++++++++++++++++++++++++++++++ > 2 files changed, 157 insertions(+) > create mode 100644 include/linux/cmdline.h > > diff --git a/include/linux/cmdline.h b/include/linux/cmdline.h > new file mode 100644 > index 000000000000..00929b6e49e6 > --- /dev/null > +++ b/include/linux/cmdline.h > @@ -0,0 +1,89 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +#ifndef _LINUX_CMDLINE_H > +#define _LINUX_CMDLINE_H > + > +/* > + * > + * Copyright (C) 2006,2021. Cisco Systems, Inc. > + * > + * Generic Append/Prepend cmdline support. > + */ > + > +#if defined(CONFIG_GENERIC_CMDLINE) && defined(CONFIG_CMDLINE_BOOL) > + > +#ifndef CONFIG_CMDLINE_OVERRIDE > +#define GENERIC_CMDLINE_NEED_STRLCAT > +/* > + * This function will append or prepend a builtin command line to the command > + * line provided by the bootloader. Kconfig options can be used to alter > + * the behavior of this builtin command line. > + * @dest: The destination of the final appended/prepended string > + * @src: The starting string or NULL if there isn't one. > + * @tmp: temporary space used for prepending > + * @length: the maximum length of the strings above. > + * @cmdline_strlcpy: point to a compatible strlcpy > + * @cmdline_strlcat: point to a compatible strlcat > + */ > +static inline void > +__cmdline_add_builtin(char *dest, const char *src, char *tmp, unsigned long length, > + size_t (*cmdline_strlcpy)(char *dest, const char *src, size_t size), > + size_t (*cmdline_strlcat)(char *dest, const char *src, size_t count)) > +{ > + if (src != dest && src != NULL) { > + cmdline_strlcpy(dest, " ", length); > + cmdline_strlcat(dest, src, length); > + } > + > + if (sizeof(CONFIG_CMDLINE_APPEND) > 1) This test can probably be avoided. if CONFIG_CMDLINE_APPEND is empty, it will add a space at the end of dest, that's harmless. > + cmdline_strlcat(dest, " " CONFIG_CMDLINE_APPEND, length); > + > + if (sizeof(CONFIG_CMDLINE_PREPEND) > 1) { Same. Keep it simple. Provide tmp all the time, have only one logic. > + cmdline_strlcpy(tmp, CONFIG_CMDLINE_PREPEND " ", length); > + cmdline_strlcat(tmp, dest, length); > + cmdline_strlcpy(dest, tmp, length); > + } > +} > + > +#define cmdline_add_builtin_custom(dest, src, length, label, cmdline_strlcpy, cmdline_strlcat) \ > +{ \ > + if (sizeof(CONFIG_CMDLINE_PREPEND) > 1) { \ > + static label char cmdline_tmp_space[length]; \ > + __cmdline_add_builtin(dest, src, cmdline_tmp_space, length, cmdline_strlcpy, cmdline_strlcat); \ > + } else if (sizeof(CONFIG_CMDLINE_APPEND) > 1) { \ > + __cmdline_add_builtin(dest, src, NULL, length, cmdline_strlcpy, cmdline_strlcat); \ > + } \ No need to micro-optimise this, you can provide cmdline_tmp_space all the time and only keep on leg of the if/elseif > +} > +#define cmdline_add_builtin(dest, src, length) \ > + cmdline_add_builtin_custom(dest, src, length, __initdata, strlcpy, strlcat) > + > +#else /* CONFIG_CMDLINE_OVERRIDE */ > + > +static inline void > +__cmdline_add_builtin_custom(char *dest, const char *src, unsigned long length, > + size_t (*cmdline_strlcpy)(char *dest, const char *src, size_t size)) Argh ! So the same function as different semantics whether CONFIG_CMDLINE_OVERRIDE and/or CONFIG_CMDLINE_BOOL is selected ? It means the architecture will have to know it as well in order to call it right ? That looks like micro-optimisation, I think it is not worth it. > +{ > + cmdline_strlcpy(dest, CONFIG_CMDLINE_PREPEND " " CONFIG_CMDLINE_APPEND, length); > +} > +#define cmdline_add_builtin_custom(dest, src, length, label, cmdline_strlcpy, cmdline_strlcat) \ > + __cmdline_add_builtin_custom(dest, src, length, cmdline_strlcpy) > +#define cmdline_add_builtin(dest, src, length) \ > + __cmdline_add_builtin_custom(dest, src, length, strlcpy) > +#endif /* !CONFIG_CMDLINE_OVERRIDE */ > + > +#else /* !CONFIG_GENERIC_CMDLINE || !CONFIG_CMDLINE_BOOL */ > + > +static inline void > +__cmdline_add_builtin_custom(char *dest, const char *src, unsigned long length, > + size_t (*cmdline_strlcpy)(char *dest, const char *src, size_t size)) > +{ > + if (src != NULL) > + cmdline_strlcpy(dest, src, length); > +} > +#define cmdline_add_builtin_custom(dest, src, length, label, cmdline_strlcpy, cmdline_strlcat) \ > + __cmdline_add_builtin_custom(dest, src, length, cmdline_strlcpy) > +#define cmdline_add_builtin(dest, src, length) \ > + __cmdline_add_builtin_custom(dest, src, length, strlcpy) \ > + > +#endif /* CONFIG_GENERIC_CMDLINE */ > + > +#endif /* _LINUX_CMDLINE_H */ > diff --git a/init/Kconfig b/init/Kconfig > index 29ad68325028..28363ab07cd4 100644 > --- a/init/Kconfig > +++ b/init/Kconfig > @@ -2032,6 +2032,74 @@ config PROFILING > config TRACEPOINTS > bool > > +config GENERIC_CMDLINE > + bool > + > +if GENERIC_CMDLINE > + > +config CMDLINE_BOOL > + bool "Built-in kernel command line" > + help > + Allow for specifying boot arguments to the kernel at > + build time. On some systems (e.g. embedded ones), it is > + necessary or convenient to provide some or all of the > + kernel boot arguments with the kernel itself (that is, > + to not rely on the boot loader to provide them.) > + > + To compile command line arguments into the kernel, > + set this option to 'Y', then fill in the > + the boot arguments in CONFIG_CMDLINE. CONFIG_CMDLINE doesn't exist. > + > + Systems with fully functional boot loaders (i.e. non-embedded) > + should leave this option set to 'N'. > + > +config CMDLINE_APPEND > + string "Built-in kernel command string append" > + depends on CMDLINE_BOOL I think it would be better to have CMDLINE_APPEND and CMDLINE_PREPENT defined at all time, and not leak CMDLINE_BOOL into code. It should just be used here to unable user customisation of CMDLINE_APPEND, as follows: config CMDLINE_APPEND string "Built-in kernel command string append" if CMDLINE_BOOL default "" > + default "" > + help > + Enter arguments here that should be compiled into the kernel > + image and used at boot time. If the boot loader provides a > + command line at boot time, this string is appended to it to > + form the full kernel command line, when the system boots. > + > + However, you can use the CONFIG_CMDLINE_OVERRIDE option to > + change this behavior. > + > + In most cases, the command line (whether built-in or provided > + by the boot loader) should specify the device for the root > + file system. > + > +config CMDLINE_PREPEND > + string "Built-in kernel command string prepend" > + depends on CMDLINE_BOOL Same comment as for CMDLINE_APPEND > + default "" > + help > + Enter arguments here that should be compiled into the kernel > + image and used at boot time. If the boot loader provides a > + command line at boot time, this string is prepended to it to > + form the full kernel command line, when the system boots. > + > + However, you can use the CONFIG_CMDLINE_OVERRIDE option to > + change this behavior. > + > + In most cases, the command line (whether built-in or provided > + by the boot loader) should specify the device for the root > + file system. > + > +config CMDLINE_OVERRIDE > + bool "Built-in command line overrides boot loader arguments" > + depends on CMDLINE_BOOL > + help > + Set this option to 'Y' to have the kernel ignore the boot loader > + command line, and use ONLY the built-in command line. In this case > + append and prepend strings are concatenated to form the full > + command line. > + > + This is used to work around broken boot loaders. This should > + be set to 'N' under normal conditions. In powerpc, by default, when a CMDLINE is provided, it is used only if the bootloader doesn't provide a command line. I can't see how I can do that here. > +endif > + > endmenu # General setup > > source "arch/Kconfig" >
diff --git a/include/linux/cmdline.h b/include/linux/cmdline.h new file mode 100644 index 000000000000..00929b6e49e6 --- /dev/null +++ b/include/linux/cmdline.h @@ -0,0 +1,89 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_CMDLINE_H +#define _LINUX_CMDLINE_H + +/* + * + * Copyright (C) 2006,2021. Cisco Systems, Inc. + * + * Generic Append/Prepend cmdline support. + */ + +#if defined(CONFIG_GENERIC_CMDLINE) && defined(CONFIG_CMDLINE_BOOL) + +#ifndef CONFIG_CMDLINE_OVERRIDE +#define GENERIC_CMDLINE_NEED_STRLCAT +/* + * This function will append or prepend a builtin command line to the command + * line provided by the bootloader. Kconfig options can be used to alter + * the behavior of this builtin command line. + * @dest: The destination of the final appended/prepended string + * @src: The starting string or NULL if there isn't one. + * @tmp: temporary space used for prepending + * @length: the maximum length of the strings above. + * @cmdline_strlcpy: point to a compatible strlcpy + * @cmdline_strlcat: point to a compatible strlcat + */ +static inline void +__cmdline_add_builtin(char *dest, const char *src, char *tmp, unsigned long length, + size_t (*cmdline_strlcpy)(char *dest, const char *src, size_t size), + size_t (*cmdline_strlcat)(char *dest, const char *src, size_t count)) +{ + if (src != dest && src != NULL) { + cmdline_strlcpy(dest, " ", length); + cmdline_strlcat(dest, src, length); + } + + if (sizeof(CONFIG_CMDLINE_APPEND) > 1) + cmdline_strlcat(dest, " " CONFIG_CMDLINE_APPEND, length); + + if (sizeof(CONFIG_CMDLINE_PREPEND) > 1) { + cmdline_strlcpy(tmp, CONFIG_CMDLINE_PREPEND " ", length); + cmdline_strlcat(tmp, dest, length); + cmdline_strlcpy(dest, tmp, length); + } +} + +#define cmdline_add_builtin_custom(dest, src, length, label, cmdline_strlcpy, cmdline_strlcat) \ +{ \ + if (sizeof(CONFIG_CMDLINE_PREPEND) > 1) { \ + static label char cmdline_tmp_space[length]; \ + __cmdline_add_builtin(dest, src, cmdline_tmp_space, length, cmdline_strlcpy, cmdline_strlcat); \ + } else if (sizeof(CONFIG_CMDLINE_APPEND) > 1) { \ + __cmdline_add_builtin(dest, src, NULL, length, cmdline_strlcpy, cmdline_strlcat); \ + } \ +} +#define cmdline_add_builtin(dest, src, length) \ + cmdline_add_builtin_custom(dest, src, length, __initdata, strlcpy, strlcat) + +#else /* CONFIG_CMDLINE_OVERRIDE */ + +static inline void +__cmdline_add_builtin_custom(char *dest, const char *src, unsigned long length, + size_t (*cmdline_strlcpy)(char *dest, const char *src, size_t size)) +{ + cmdline_strlcpy(dest, CONFIG_CMDLINE_PREPEND " " CONFIG_CMDLINE_APPEND, length); +} +#define cmdline_add_builtin_custom(dest, src, length, label, cmdline_strlcpy, cmdline_strlcat) \ + __cmdline_add_builtin_custom(dest, src, length, cmdline_strlcpy) +#define cmdline_add_builtin(dest, src, length) \ + __cmdline_add_builtin_custom(dest, src, length, strlcpy) +#endif /* !CONFIG_CMDLINE_OVERRIDE */ + +#else /* !CONFIG_GENERIC_CMDLINE || !CONFIG_CMDLINE_BOOL */ + +static inline void +__cmdline_add_builtin_custom(char *dest, const char *src, unsigned long length, + size_t (*cmdline_strlcpy)(char *dest, const char *src, size_t size)) +{ + if (src != NULL) + cmdline_strlcpy(dest, src, length); +} +#define cmdline_add_builtin_custom(dest, src, length, label, cmdline_strlcpy, cmdline_strlcat) \ + __cmdline_add_builtin_custom(dest, src, length, cmdline_strlcpy) +#define cmdline_add_builtin(dest, src, length) \ + __cmdline_add_builtin_custom(dest, src, length, strlcpy) \ + +#endif /* CONFIG_GENERIC_CMDLINE */ + +#endif /* _LINUX_CMDLINE_H */ diff --git a/init/Kconfig b/init/Kconfig index 29ad68325028..28363ab07cd4 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -2032,6 +2032,74 @@ config PROFILING config TRACEPOINTS bool +config GENERIC_CMDLINE + bool + +if GENERIC_CMDLINE + +config CMDLINE_BOOL + bool "Built-in kernel command line" + help + Allow for specifying boot arguments to the kernel at + build time. On some systems (e.g. embedded ones), it is + necessary or convenient to provide some or all of the + kernel boot arguments with the kernel itself (that is, + to not rely on the boot loader to provide them.) + + To compile command line arguments into the kernel, + set this option to 'Y', then fill in the + the boot arguments in CONFIG_CMDLINE. + + Systems with fully functional boot loaders (i.e. non-embedded) + should leave this option set to 'N'. + +config CMDLINE_APPEND + string "Built-in kernel command string append" + depends on CMDLINE_BOOL + default "" + help + Enter arguments here that should be compiled into the kernel + image and used at boot time. If the boot loader provides a + command line at boot time, this string is appended to it to + form the full kernel command line, when the system boots. + + However, you can use the CONFIG_CMDLINE_OVERRIDE option to + change this behavior. + + In most cases, the command line (whether built-in or provided + by the boot loader) should specify the device for the root + file system. + +config CMDLINE_PREPEND + string "Built-in kernel command string prepend" + depends on CMDLINE_BOOL + default "" + help + Enter arguments here that should be compiled into the kernel + image and used at boot time. If the boot loader provides a + command line at boot time, this string is prepended to it to + form the full kernel command line, when the system boots. + + However, you can use the CONFIG_CMDLINE_OVERRIDE option to + change this behavior. + + In most cases, the command line (whether built-in or provided + by the boot loader) should specify the device for the root + file system. + +config CMDLINE_OVERRIDE + bool "Built-in command line overrides boot loader arguments" + depends on CMDLINE_BOOL + help + Set this option to 'Y' to have the kernel ignore the boot loader + command line, and use ONLY the built-in command line. In this case + append and prepend strings are concatenated to form the full + command line. + + This is used to work around broken boot loaders. This should + be set to 'N' under normal conditions. +endif + endmenu # General setup source "arch/Kconfig"